Spark-plug.



J. R.. MODOW'ELL.

SPARK PLUG.

APPLICATION FILED MAY 24, 1912.

Patented Mar". 3, 1914.

JOHN R. MCDOWELL, oF AUBURN, INDIANA.

SPARK-PLUG.'

Specification of Letters Patent.

Patented Mar. 3, 1914.

Application led May 24., i912. Serial N o. 699,442.

To all whom it may concern Be it known'that I, JOHN R. McDowELL, a citizen of the United States, residing at Anburn,'i1rtbe county vof Dekalb and State of Indiana, .have invented new and useful VImprovements in Spark-Plugs, of which the following is a specification.

This invention relates tos ark plugs, the object in view being to provi e a spar z plug having two decided points of advantage, the

first of "which is to` prolong and extend thel spark as it jumps between 'the points, and

vsecondly to provide for aready cleaning away of any matter which mayaccumulate between the pointsof the plug, the cleaning away of sucbmaterial Abeing effected by the explosion or rapid movement of the gases 'in thecombustion space of the cylinder, in connection with which the plug is used.

VWith the above and other objects in view, the invention consists in the construction, combination and arrangement of parts, as will be hereinafter more fully described, illustrated in theaccompa'n'ying drawings, and pointed-out in the claimhereunto appended. .l

In the drawings: .Figure lis a side ele-- ration of a spark plug, embodying the presentinvention. Fig. 2 is an end View, look ing Atoward the soparking points thereof., Fig. Bis a longitu inal section through the spark plug, taken inline with the igniterpoints. A l

Referringv to" the drawings, 1 designates the outer metal jacket of the spark plug, and 2 the usual` confining plug which is threaded inthe outer'end of the main body ofthe plug, for the purpose-'of holding the core in place therein.

3 designates the core which is usually made of porcelain or other good insulating material, the same being provided with a .positioning flange 4, against which the confining plug 2v bears, when the parts of th'e plug are brought into their final assembled positions. Altxtendiiug Alengthwise through the core 3 is the wi'rev "which termina-tes tov at one end -in the live or spark poi-nt 6, and at the other end in the binding post ln the preferred embodiment ofjthis'invent-ion, an\igrfiter. point 8 extends inward Y from the met-al j'acfket 1, although such point 8 is not essential, as the casing itself may be used as theouter spark point.

In carrying out the present invention, l

locatel a dead point 9 between the spark point 5 and the ou'ter shell or jacketthus causing a double spark, or in otherwords, causing the spark to jump in two places between the spark point and the dead point,

and between the dead point and the outer shell or casing. This has the effect of making two sparks, or in other words, a spark of double length, thus adding` materially to linsure the igniting of the charge contained in the combustion space of the cylinder. Furthermore the dead point, it will "be observed, is concaved or recessedon both ymyself to any particular number of dead points, as quite a number may be located between the spark point and the outer casing, or in other Words, betweenthe spark point carried by the porcelain core and the outer shell orjacket. By using a greater number of these dead points, the spark may be prolonged or extended to a very considerable extent, and by concaving or .recessing the dead points on opposite sides, any material, such as carbon, which-may accumulate between the points will be blown out by the rapid movement of the gases in the explo- =s1on`1n the combustion chamber.

Furthermore, it has been found in practice that the spark in its second jump, or in other words, after leaving the dead point is more intense than in the initial jump before it reaches the dead point. A l

The inner end 'of the core is providedwith a central conical recess, as shown at 10, so as to give clearance around the ignition points and prevent danger of corrosion of the points themselves. This recesswill also materially assist in breaking up any carbon deposit on the extremities of the points. For a like purpose the outer edge of the inner -end of'the plug is beveled, forming a V-shaped annular ridge from the -a `,eX 'of which the dead-point 9 projcets, sai dead point being located in radial line between the igniter joint and jacket. Furthermore,

should matter accumulate between two of the points, so as to prevent the jumping of such spark at such place, the spark Will still jump across the points between which there is no obstructing matter.

What is claimed is:

A spark plug, comprising a metal jacket, an insulating core therein having the inner end thereof formed With a central recess .and its outer edge beveled, leaving a V- shaped annulairldge, a spark point protruding from the core centrally of said rey cess and partially arranged in said recess,

and a dead point projecting from the apex4 of said ridge and lying in a radial line between the spark point and the jacket, the dead point being concaved ,on both sides back of the yextremity thereof and .the spark point being concaved on the side next to the dead point.

In testimony whereof I affix my signature in presence of two Witnesses.

JOHN R. MCDOVELL. lVitnesses Dr. A. M. OSW/ALT, FRANK P. THOMAS. 

